Publications by authors named "Hans Jurgen von Bardeleben"

High-spin defects (color centers) in wide-gap semiconductors are considered as a basis for the implementation of quantum technologies due to the unique combination of their spin, optical, charge, and coherent properties. A silicon carbide (SiC) crystal can act as a matrix for a wide variety of optically active vacancy-type defects, which manifest themselves as single-photon sources or spin qubits. Among the defects, the nitrogen-vacancy centers () are of particular importance.

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As the development of aluminum-ion batteries is still in its infancy, researchers are still dedicated to exploring suitable host materials and investigating their aluminum intercalation behaviours. Here, a series of cyanido-bridged chain compounds with the formula {[Fe(Tp)(CN)][M(HO)]} (M = Ni, Co, Mn, Zn, Cu) are studied as cathode electrodes for aluminum-ion batteries with [EMIm]Cl-AlCl (1-ethyl-3-methylimidazolium chloride-AlCl) ionic liquid as the electrolyte. The electrochemical properties suggested Fe/Fe to be the redox-active couple during the aluminum intercalation and deintercalation processes of these compounds, and the observed maximum specific capacity obtained by the Fe-Co compound is 200 mA h g despite the rapid specific capacity fading.

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FeCo Prussian blue analogues of general formula ACo[Fe(CN)] are responsive, non-stoichiometric materials whose magnetic and optical properties can be reversibly switched by light irradiation. However, elucidating the critical influence of the inserted alkali ion, A, on the material's properties remains complicated due to their complex local structure. Here, by investigating soluble A ⊂ [Fe-Co] cyanido cubes (A = K, Rb, and Cs), both accurate structural and electronic information could be obtained.

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The nitrogen-vacancy (NV) center in 3-SiC, the analog of the NV center in diamond, has recently emerged as a solid-state qubit with competitive properties and significant technological advantages. Combining first-principles calculations and magnetic resonance spectroscopy, we provide thorough insight into its magneto-optical properties. By applying resonantly excited electron paramagnetic resonance spectroscopy, we identified the zero-phonon absorption line of the → transition at 1289 nm (within the telecom O-band) and measured its phonon sideband, the analysis of which reveals a Huang-Rhys factor of = 2.

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Silicon carbide (SiC) has become a key player in the realization of scalable quantum technologies due to its ability to host optically addressable spin qubits and wafer-size samples. Here, we have demonstrated optically detected magnetic resonance (ODMR) with resonant excitation and clearly identified the ground state energy levels of the NV centers in 4H-SiC. Coherent manipulation of NV centers in SiC has been achieved with Rabi and Ramsey oscillations.

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We report the enhancement of the optical emission between 850 and 1400 nm of an ensemble of silicon mono-vacancies (V), silicon and carbon divacancies (VV), and nitrogen vacancies (NV) in an n-type 4H-SiC array of micropillars. The micropillars have a length of ca. 4.

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Octahedral molecular sieves (OMS) are built of transition metal-oxygen octahedra that delimit sub-nanoscale cavities. Compared to other microporous solids, OMS exhibit larger versatility in properties, provided by various redox states and magnetic behaviors of transition metals. Hence, OMS offer opportunities in electrochemical energy harnessing devices, including batteries, electrochemical capacitors and electrochromic systems, provided two conditions are met: fast exchange of ions in the micropores and stability upon exchange.

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Single-photon emitters (SPEs) play an important role in a number of quantum information tasks such as quantum key distributions. In these protocols, telecom wavelength photons are desired due to their low transmission loss in optical fibers. In this paper, we present a study of bright single-photon emitters in cubic silicon carbide (3C-SiC) emitting in the telecom range.

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